FIG. 9 shows a conventional circuit protecting element (disclosed in Patent Document 1) comprising the following structural elements:                insulating substrate 1;        a pair of surface electrodes 2 provided to both ends of the top face of substrate 1;        base layer 3 made of epoxy resin formed on the top face of substrate 1;        element 4 electrically connected to the pair of surface electrodes 2 on the top face of base layer 3;        insulating layer 5 covering element 4; and        a pair of shoulder electrode layers 6 formed on both ends of substrate 1.        
Base layer 3 of the foregoing conventional circuit protecting element; however, is made of epoxy resin having a low heat resistance, so that its shape becomes unstable due to the heat produced by a laser beam with which trimming grooves are formed on element 4. This unstable shape of base layer 3 sometimes causes the shape of element 4 to be unstable, which invites dispersion in the blowout characteristics of the circuit protecting element.
Patent Document 1: Unexamined Japanese Patent Application Publication No. H05-225892